High speed turbo machinery, e.g., turbo-expanders, is used in a variety of industrial applications such as in the production of industrial gases the fractional distillation of air. Fractional distillation of air is used to produce oxygen, nitrogen, argon, and the like. In these processes, turbo expanders are used to reduce the pressure of the air and/or the individual gases components.
Compliant foil gas bearings have been applied successfully to a wide range of high speed rotating machinery. These gas foil-type bearings are especially attractive to turbo expanders because they eliminate the lube oil system, simplify the seal gas system, simplify the control system, offer lower frictional power loss and provide greater flexibility of machine installation.
U.S. Pat. No. 3,893,733; 4,133,585; 4,167,295; 4,262,975; and 4,300,806 are examples of compliant foil gas (hydrodynamic) bearings. The prior art compliant hydrodynamic bearings rely upon a bump foil and a smooth foil which are fastened to the inside surface of a journal bearing. The bump foil has a series of uniform corrugations (bumps) which are aligned generally parallel to the longitudinal axis of the sleeve. In the past, attempts have been made to change the configuration of the bump foil in order to improve the load carrying capacity without sacrificing compliance required for Coulomb damping of the sleeve bearings.